With the development of sophisticated methods for manufacturing micrometer structures in a controlled way, devices based on microelectromechanical system (MEMS) technology has become more attractive. One important type of device which has found a vast number of applications is the MEMS-based gyroscope. Such a device has great importance in e.g. navigation, positioning, and tracking of devices, but also for monitoring and controlling mechanical stability of apparatuses onto which a MEMS gyroscope may be mounted.
A great challenge in manufacturing a MEMS gyroscope is to achieve a reliable manufacturing method for fabricating sufficiently well-balanced gyroscope devices, preferably in a mass-production line. Such a gyroscope device typically comprises a number of interconnected inertial masses which may be excited to rotate or vibrate about an excitation axis during operation. Detection of a rotational motion is performed by detecting a deflection of the inertial mass about a detection axis influenced by the corolis force. However, manufacturing defects may introduce asymmetry in the gyroscope which may affect the operation in a negative way. For example, if the gyroscope is not well-balanced, external vibrations may excite vibration modes of the gyroscope, thus distorting also the sense mode causing a relatively high error in the output signal.
In order to avoid the external vibrations the gyroscope may have to be isolated from the sources of vibration, or only well-balanced gyroscopes are used, which effectively leads to low fabrication yields.
U.S. Pat. No. 6,467,349 discloses a MEMS gyroscope with relatively good performance for several applications, for example in the automotive industry. However, it would be desirable to reduce the impact of external vibrations on such a gyroscope in order to further improve the performance.
Thus, there is a need for more robust gyroscope sensor which is less sensitive to external vibrations with an improved structural configuration.